PROJECT SUMMARY In spite of well-known changes in cognitive abilities with aging, emotion regulation improves over the course of healthy aging. As such, understanding how emotions are regulated and how these processes change across adulthood will inform prevention and treatment of deficits in emotion processing that accompany mood disorders, Alzheimer's disease, and other pathologies. The long-term objective of this line of research is to understand the function of sleep and particularly the implications of sleep function on enhancing well-being with aging. The specific objective of the proposed research is to understand the role of sleep in emotion regulation across adulthood. The overarching hypothesis is that sleep contributes to the positive bias in emotion processing that emerges with aging. Aim 1 is to examine whether a positive bias in sleep-dependent processing of memory develops with aging. Recognition of emotional images both immediately after encoding and following intervals of sleep or wake will be examined in young, middle-aged, and older adults. Aim 2 is to examine whether a positive bias in sleep-dependent processing of emotional reactivity develops with aging. Subjective ratings of emotional images and physiological markers of reactivity (heart rate, skin conductance, and facial muscle activity) will be assessed in young, middle-aged, and older adults during encoding and following a nap or wake interval. It is hypothesized that young adults preferentially consolidate negative emotional memories while older adults preferentially consolidate positive emotional memories over sleep. This emotional bias, in turn, is hypothesized to contribute to changes in mood post-sleep. Furthermore, proposed studies will consider the role of the emotional bias at encoding and specific aspects of sleep physiology in the age-related change in sleep-dependent emotional processing. The proposed research is innovative, introducing sleep as a novel construct by which to examine the positivity bias in healthy aging. The outcomes of this work have theoretical significance. First, these results will increase our understanding of age-related changes in emotion processing. Second, our results will provide mechanistic insight into the positivity bias, identifying specific relevant aspects of sleep and incorporating both subjective and objective measures of emotion. The outcomes will also have translational significance. This research is essential for establishing the extent to which sleep can be considered a therapeutic target and whether this depends on age. By defining the role of sleep in healthy older adults, we can then turn to populations in which sleep and emotion processing are impaired, such as in individuals with Alzheimer's disease, and examine whether sleep deficits can account for emotional dysregulation.